1. Field of the Invention
The present invention relates to an automatic central buffer coupling, especially of the “Tightlock/AAR” type of construction, for a multi-member rail vehicle.
2. Description of the Related Art
Coupling and decoupling of trains is a principle known from rail vehicle technology. When mechanical couplings are used to connect two adjacent car bodies, the coupling claw of the first car body is force-fit with the coupling claw of the other car body so as to transfer tractive force and momentum between the two car bodies mechanically coupled in this way.
Apart from the mechanical coupling of adjacent car bodies, electrical lines such as power and data cables are usually in simultaneous use, co-coupled by a plurality of contact terminals arranged on one electrical contact carrier. Moreover, a simultaneous co-coupling of compressed air lines should be provided. The simultaneous co-coupling of line couplings (electrical cables and compressed air lines) with the mechanical coupling operation requires, especially with respect to the contact terminals of the electrical connection, that the mechanical connection created between the two coupling heads of the adjacent car bodies be a rigid system or one which can be made rigid in order to ensure the necessary contact pressure and especially to avoid arcs occurring between the co-coupled contact terminals.
It is known, for example from DE 241 43 84 A1, that for the mechanical coupling of adjacent car bodies, the coupling head is to be designed such that the head has a plane front face disposed transversely to the longitudinal axis at the forward, front face end in the coupling plane which contacts the corresponding abutment surface of the mated coupling. A compressed air terminal is moreover hereto provided on or in said abutment surface for the co-coupling of a compressed air line.
However, the principle behind this arrangement, in which the rigid and play-free front faces of the respective car bodies meet does not readily allow the introduction of a central buffer coupling for certain types of construction, particularly in the case of claw couplings, for example those of the “AAR” (American Association of Railway) or “Tightlock” type, that there is in fact no front face or abutment surface disposed transversely to the longitudinal axis. Moreover, all the coupling heads of such constructional types basically still exhibit a certain amount of play during the coupling process such that longitudinal and transverse movements occur between the respective coupling heads which necessitate making the corresponding compensation in order to thereby enable efficient co-coupling of the electrical contact carrier and above all avoid the occurrence of material-damaging arcs at the contact terminals.
With the development of an automatic central buffer coupling based on the principle of a claw coupling, it is of fundamental importance to have an economical and flatly constructed solution for the design and arrangement of an electrical contact coupling and an air line coupling which are co-coupled together with the mechanical coupling of the coupling head. However, because of the high degree of play and the constant movement thereby seen in conjunction with such types of couplings, applicable solutions are only realizable given considerable technical or economical expenditure. Furthermore, in practice, such solutions can only be realized with difficulties or limitations since vertically tall-constructed central buffer couplings of the claw coupling type most notably lack the necessary installation spaces and clearances for installing an electrical contact coupling and/or the air line coupling.
Conversely, the example of AAR couplings are noted for their simple design, sturdy construction, high stability and low price. A further advantage is to be seen in that AAR couplings are universally applicable, in particular referring both to passenger as well as freight trains. These aspects have led to a worldwide interest in finding a solution to the problems cited above related to the automatic co-coupling of the electrical contact coupling and the air line coupling for these types of central buffer couplings which would be as readily feasible and economical as possible.
An electrical contact coupling for central buffer couplings, particularly for the example of claw couplings of the “AAR” type, is known from EP 1 102 696 A1, in which an electrical contact coupling is arranged underneath the mechanical coupling head in such a manner so as to be longitudinally displaceable in the longitudinal direction of the central buffer coupling. The electrical contact coupling is thereby disposed to be displaced rearward of the coupling plane in the uncoupled state. In this position, due to the design-contingent play of the coupling head, damage to the electrical contact carrier can be largely avoided when the coupling head moves along the coupling plane. While centering elements and interlocking points are provided on the electrical contact couplings for improving the contact pressure in accordance with the above-cited document, the solution indicated does not consider the problem of there still being increased play in the mechanical coupling. On the one hand, this leads to high stressing of the electrical contacts and, on the other, not being able to consistently guarantee a sound contact between two coupled electrical contact couplings.
Moreover, in the case of the coupling head in accordance with EP 1 102 696 A1, the pneumatic/hydraulic coupling of train members is effected by a fixed and elastic connection of the air coupling to the head. This necessitates the fixed air coupling terminals absorbing the mechanical play of the heads; however, this is only possible to a limited extent. Also to prove problematic with the proposed solution is the use of elastomeric blocks to secure one of the supporting units for the electrical contact coupling to the coupling head to enable a fixed but yet elastic connection to be made between the coupling head and the supporting unit. It turns out here that by using elastic elements for the connection, the play in the mechanical locking is transferred directly to the electrical contact coupling, which can lead to contact problems.
Starting from the subject matter of EP 1 102 698 A1 as a basis, the problem therefore facing the present invention is that electrical contact terminals have to date been subject to high stress during the co-coupling of electrical contact couplings in light of the simultaneous mechanical and electrical coupling operations in central buffer couplings of the AAR or Tightlock type and, because of the higher play seen in these types of couplings, a reduction in contact pressure and possible arcs can occur, and due to the higher play in the case of air couplings, compressed air losses, referred to as blowoff, can occur.